<template>
  <el-card class="box-card">
    <div class="clearfix">
      <h3>员工导入</h3>
      <p>
        <i class="el-icon-warning"> </i>
        每次导入仅可添加1000名员工，姓名、手机、入职时间、聘用形式为必填项
      </p>
    </div>
    <div class="excel-box">
      <div class="excel-btn">
        <el-button
          :loading="loading"
          style="margin-left:16px;"
          size="mini"
          type="primary"
          @click="handleUpload"
        >
          点击上传
        </el-button>
      </div>
      <input
        ref="excel-upload-input"
        class="excel-upload-input"
        type="file"
        accept=".xlsx, .xls"
        @change="handleClick"
      />
      <div
        class="drop"
        @drop="handleDrop"
        @dragover="handleDragover"
        @dragenter="handleDragover"
      >
        <i class="el-icon-folder-add"></i><br />
        Drop excel file here or
      </div>
    </div>
  </el-card>
</template>

<script>
import XLSX from 'xlsx'

export default {
  props: {
    beforeUpload: Function, // eslint-disable-line
    onSuccess: Function // eslint-disable-line
  },
  data () {
    return {
      loading: false,
      excelData: {
        header: null,
        results: null
      }
    }
  },
  methods: {
    generateData ({ header, results }) {
      this.excelData.header = header
      this.excelData.results = results
      this.onSuccess && this.onSuccess(this.excelData)
    },
    handleDrop (e) {
      e.stopPropagation()
      e.preventDefault()
      if (this.loading) return
      const files = e.dataTransfer.files
      if (files.length !== 1) {
        this.$message.error('Only support uploading one file!')
        return
      }
      const rawFile = files[0] // only use files[0]

      if (!this.isExcel(rawFile)) {
        this.$message.error(
          'Only supports upload .xlsx, .xls, .csv suffix files'
        )
        return false
      }
      this.upload(rawFile)
      e.stopPropagation()
      e.preventDefault()
    },
    handleDragover (e) {
      e.stopPropagation()
      e.preventDefault()
      e.dataTransfer.dropEffect = 'copy'
    },
    handleUpload () {
      this.$refs['excel-upload-input'].click()
    },
    handleClick (e) {
      const files = e.target.files
      const rawFile = files[0] // only use files[0]
      if (!rawFile) return
      this.upload(rawFile)
    },
    upload (rawFile) {
      this.$refs['excel-upload-input'].value = null // fix can't select the same excel

      if (!this.beforeUpload) {
        this.readerData(rawFile)
        return
      }
      const before = this.beforeUpload(rawFile)
      if (before) {
        this.readerData(rawFile)
      }
    },
    readerData (rawFile) {
      this.loading = true
      return new Promise((resolve, reject) => {
        const reader = new FileReader()
        reader.onload = e => {
          const data = e.target.result
          const workbook = XLSX.read(data, { type: 'array' })
          const firstSheetName = workbook.SheetNames[0]
          const worksheet = workbook.Sheets[firstSheetName]
          const header = this.getHeaderRow(worksheet)
          const results = XLSX.utils.sheet_to_json(worksheet)
          this.generateData({ header, results })
          this.loading = false
          resolve()
        }
        reader.readAsArrayBuffer(rawFile)
      })
    },
    getHeaderRow (sheet) {
      const headers = []
      const range = XLSX.utils.decode_range(sheet['!ref'])
      let C
      const R = range.s.r
      /* start in the first row */
      for (C = range.s.c; C <= range.e.c; ++C) {
        /* walk every column in the range */
        const cell = sheet[XLSX.utils.encode_cell({ c: C, r: R })]
        /* find the cell in the first row */
        let hdr = 'UNKNOWN ' + C // <-- replace with your desired default
        if (cell && cell.t) hdr = XLSX.utils.format_cell(cell)
        headers.push(hdr)
      }
      return headers
    },
    isExcel (file) {
      return /\.(xlsx|xls|csv)$/.test(file.name)
    }
  }
}
</script>

<style scoped lang="scss">
.box-card {
  margin: 20px 25px;
  .clearfix {
    h3 {
      text-align: center;
    }
    p {
      font-size: 14px;
      line-height: 30px;
      height: 30px;
      color: #ecaa3c;
      background-color: #fdf6ec;
      i {
        margin: 0 5px 0 10px;
      }
    }
  }
}
.excel-box {
  height: 65vh;
  display: flex;
  justify-content: center;
  align-items: center;
  .excel-upload-input {
    display: none;
    z-index: -9999;
  }
  .excel-btn {
    line-height: 160px;
  }
  .excel-btn,
  .drop {
    border: 1px dashed #bbb;
    width: 450px;
    height: 160px;
    border-radius: 5px;
    text-align: center;
  }
  .drop {
    font-size: 24px;
    border-radius: 5px;
    text-align: center;
    color: #bbb;
    i {
      font-size: 60px;
      margin: 15px 0 15px;
    }
  }
}
</style>
